[Apex] Is InterfaceNames available to be used in a custom XPath rule?

[thvd]

Context:

Given i have an apex class implementing Queueable interface. Using PMD i want to ensure that always also the Finalizer interface is also implemented to handle exceptions, to for example write them to a log.

The question i have is are the implemented interfaces available for a custom XPath rule?
I have already looked in the designer and could find it, so probably the answer is no, but i am wondering why? And is this something i can contribute to?

I could find it however in the Java code:

pmd/pmd-apex/src/main/java/net/sourceforge/pmd/lang/apex/ast/ASTUserClass.java

Line 43 in d4b99bb

public List<String> getInterfaceNames() {

[jsotuyod]

No, getters returning lists are not exposed as attributes in xpath… I think you have a legit use case here, but right now I believe it's only feasible with rules written in Java…

[oowekyala]

Getters having a list type unfortunately can not be supported in XPath because of Saxon's implementation. However it is possible to write a custom XPath function to return that.

[jsotuyod]

For completeness, I've just submitted a PR for PMD 7.1.0 that would expose collection attributes such as getInterfaceNames() as an XPath attribute through a sequence. #4969

With that you should be able to write

//UserClass[
  not(empty(index-of(@InterfaceNames, 'Queueable'))). (: implements Queueable :)
  and empty(index-of(@InterfaceNames, 'Finalizer')) (: but doesn't implement Finalizer :)
]

[oowekyala]

Not that this not(empty(index-of( is not the best way to write that in xpath. You can directly write @InterfaceNames = 'Queuable' and not(@InterfaceNames = 'Finalizable'). The equals operator tests for equality of any two members of the left and right sequence.